Re-do of M101 (4-8-10)

This is a re-process of M101 with the colors mostly figured out. This is a test to see how well it looks on several other monitors. Which is better, top or bottom?

Bubble Nebula in Narrowband (Posted 11-22-09)

I like this version the best, I think. This image was processed last. I am experimenting with Maxim DL and did an LRGB combines using the same data as the others below. Better?This is the finished narrowband Bubble Nebula, NGC 7635. The brightest star in the bubble has cleared the space around it with its strong stellar wind. The colors are mapped variously. The first image above has Ha as Green, OIII as Blue, and SII as Red.

Imaging Scope: Orion 80ED & WO 0.8x II (f/6)
Imager: Atik 16
Exposure: 45x5' in Ha; 37x5' in OIII; 47x5' in SII (10 hours, 45 minutes total)
Filter(s): Astronomik Ha (+NII), OIII, and SII
Capture Software: Nebulosity 2
Mount: Takahashi EM-10
Guiding Camera: DSI Pro
Guiding Software: PHD
Guiding Scope: 60mm f/4 hybrid
Date: October & November 2009
Location: The Woodlands, TX
Processed with Nebulosity 2, Registar, & Photoshop Elements 7

The Final Pacman, NGC 281

Here is the final for the moment, but I need to look at it for a few days.

The difference between the two is different processing in Registar. Before I combined the three sets in RGB then split them into channels only to re-combine them in Neb2 as LRGB=(Ha)HaGB. For this image, I turned auto-scaling in Registar off, then registered G and B to Ha, calibrated G and B to Ha, then saved the calibrated images. Then I went back to Neb2, aligned the Ha and calibrated G and B, saving each as separate files. Then I combined in LRGB synthesis using Ha as Lum and R, as before, then stretched and adjusted color and background until the stars began to look right. Finally, I opened in Photoshop Elements 7 for cropping, a little unsharp masking, and the application of Noel Carboni's action "Increase Star Color." I am happy with this image. It matches my data quite well.

Other details about the image can be found here.

Here is a false color version. In this rendition, Ha is blue, blue is red, and green is blue. I like it because the blue-white stars show gold against the background of the nebula. It's a nicer aesthetic effect.

NGC 40, the Bow Tie Nebula

A comparatively shallow view of this nebula looks like a bow tie. See?
But the deeper image shows the central star is actually surrounded by a boxy circle of gas (and dust?). The structure of the nebula is also bipolar, with something happening on the north and south. Just what is unclear. A stretch of gas swings out from the north, and from the south a leg is jutting out. Diffuse gas glows all around what appear to be edges of the circle. Compare my view with Don Goldman's here, taken which much larger equipment.

Here's the riddle: Why does this planetary nebula glow so strongly in an image taken with an Ha filter? A planetary is usually formed when a dying star is dying because it has used up the hydrogen reserves necessary to burn like normal a star. It then swells up like a balloon and starts blowing the outermost layers into space. If the hydrogen left is not prominent in these stars, why does this nebula glow so brightly through an Ha filter, which focuses on the spectral line of ionized hydrogen gas?

There are two answers to this question. The first answer to this question is that my Ha filter lets through not just the important wavelength of ionized hydrogen at 656.3 nm. The filter I have lets through a range of wavelengths 13 nm wide. The 13 nm are roughly centered on the H-alpha line, but the range also includes that of ionized nitrogen at 658.4 nm. So actually everything taken through my Ha filter is Ha + NII.

The second answer is that some planetary nebulae actually contain a great deal of hydrogen. One study that split Ha and NII emissions of planetary nebulae in the Magellanic Clouds (two nearby galaxies) shows that some have more Ha and some have more NII. Some images from the study are here. The upshot is that I do not know which NGC 40 shows more of, Ha or NII. Unless and until I get some even narrower narrowband filters (such as advertised here), I will not be able to discover.

Imaging Scope: Orion 80ED & WO 0.8x II (f/6)
Imager: Atik 16
Exposure: 120" x 31
Filter: Astronomik 13nm Ha + NII
Capture Software: Nebulosity 2
Mount: Takahashi EM-10
Guiding Camera: DSI Pro
Guiding Software: PHD
Guiding Scope: No-name 60mm f/5
Date: Night of 9-26-09
Location: The Woodlands, TX
Processed with Nebulosity 2, Photoshop Elements 7 with Carboni Actions.

NGC6820 & 6823

NGC 6820 is a wonderfully detailed combination of bright and dark nebulae in the constellation Vulpecula, just south and east of Albireo and just west of M27. NGC 6823 is the cluster of stars embedded in the nebula. The cluster formed from the nebula's gas. Radiation from the cluster's hot, young stars now causes the gas to glow in the ionized hydrogen line called H-alpha. Radiation from the cluster is now driving the gas away from the cluster. Where the gas resists, bright walls and dark columns form. Eventually, more stars will form from the gas, and radiation from the stars will continue to push the gas away until the gas is entirely dispersed, leaving only a large cluster of young stars. We are watching stars at birth!

The cluster and nebula sit in the bottom left of this frame because I wanted to make sure the long, dark, elephant-trunk-like column made it prominently into the final photo. I could not see the column on any of my test exposures, though it did appear in some of the 4' subs later on. Anyway, now I see that a 600mm scope does not yield a very large image, and I should have nearly centered on the cluster. But here it is, nonetheless.

My eight-year-old son thinks the larger stars in the center of the cluster look like the wings of a small bee! The dimmer stars in between look like the body, with a stinger on the end. Can you see it? It's the Bee Cluster!

Imaging Scope: Orion 80ED & WO 0.8x II (f/6)
Imager: Atik 16
Exposure: 40x4', or 160'
Filter: Astronomik 13nm Ha
Capture Software: Nebulosity 1
Mount: Takahashi EM-10
Guiding Camera: DSI Pro
Guiding Software: PHD
Guiding Scope: No-name 60mm f/5
Date: Night of 9-6-09
Location: The Woodlands, TX
Processed with Nebulosity 1, Photoshop Elements 7